what does the " ` " sign(available on the top of tab key) in a sql/pl-Sql query mean?

Question

As for Example :-

UNIQUE KEY `nbatch_id`(`nbatch_id`,`ncourse_id`,`nbranch_id`,`vstu_rollno`,`Type`)

isn't it just a single quote? basically its signaling a string — Alistair Laing, Sep 29 '14 at 21:02
That is invalid for PL/SQL. And it's invalid standard SQL - that's only valid in MySQL. — , Sep 29 '14 at 21:07

score 1 · Answer 1 · edited May 23 '17 at 12:13

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It means the same thing as the double quotation mark means in other systems.

More information about the use of the grave accent character in SQL can be found here

edited May 23 '17 at 12:13

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answered Sep 29 '14 at 21:01

Robert Harvey

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score 1 · Answer 2 · answered Sep 29 '14 at 22:04

MySQL uses the back-tick (or back-quote) character as a non-standard delimiter for SQL identifiers (table names, column names, index names, etc.).

The ANSI SQL equivalent is the double-quote ("). You can make MySQL use the double-quote as an identifier delimiter by setting SQL_MODE='ANSI_QUOTES'.

Delimited identifiers are not strings. In SQL, string literals and date literals use the straight single-quote character ('), which is on the same key as " on a US keyboard.

Delimited identifiers aren't necessary most of the time. Their purpose is to allow you to use SQL reserved words as identifiers, or identifiers containing special characters not normally allowed in an identifier. See my answer to Do different databases use different name quote?

In the example you show, none of the identifiers strictly require delimiting. But some tools add them by default, just in case you were to use a reserved word, or a table name containing a space or something.

what does the " ` " sign(available on the top of tab key) in a sql/pl-Sql query mean?

2 Answers2